Should we be using more viscous engine oil?

Try it and see... What's the worst that could happen? Slightly worse fuel consumption, maybe?

 

I've switched to adding 5w-30 Mobil 1 and don't see any difference with mpg's. I decied to do it because it's hot in the summer in Fl. and I drive a lot on the highway and other countries like Australia (where it gets hot) 5w-30 is the first choice there.

 

I feel a range of viscosity is OK, we have some lists somewhere.
However, I would not say Gen3 is designed for 5W-30.
I am thinking cars went to tighter clearances including Gen3, also less fuel getting in the oil compared to Gen2.

 

my cap says 0w-20.

 

...that's where you are off target compared to what most of us are thinking...

 

I'm sure the Gen. 3 was supposed to use 0-20 from the beginning. My 2010 which I got early in the run said 0-20 on the cap. But I still think it is just to get a mpg or 2 more for the fuel mileage tests. I would have to check again but other hot countries don't even list 0-20 as a choice. I'm pretty sure 5w-30 is the choice in quite a few other countries. I'm sure it was "designed" for either or, but maybe NOT 0-20 where it's real hot. Would love to hear what the Toyota engineers would have to say about this.

 

I'm out of my depth, but suspect it isn't "designed" for either. I'd concur 0W20 was the recommended weight from the start, smoking gun being:



That said, 5W30 sounds interesting. being the second gen spec.

 

possibly, but who would be qualified to make a different recommendation?

 

Gen 2 was an entirely different 1.5 liter engine, speced for regular oil
The Gen 3 is a 1.8 liter engine speced for 0-20 synthetic.

And yes, in other countries where it is hotter or where the oil is less refined, they spec heavier oil.

 

No downside. A3/B4 0w40's specifically are fantastic oils in gas engines. High HTHS, high quality base stock and light for 40 weights. UOA's typically show them sheared into the 30 range for a given interval. Great oil if you like to run the full 10,000 mile interval but would prefer your oil control rings to stay functional. M1, Castrol and Pennzoil Euro can all be had in the 5 qt. jugs for ~$25 at Wally in these parts, often with mail-in rebate in addition. You'll be hard pressed to notice a decrease in gas mileage, too.

 

^^^that's who^^^

 

Just my opinion. And you know what they say about opinions...

 

Here’s my opinion :

I have been using 5w-30 for 57 k miles now and our 2010 with 177k miles is running strong.

Here’s an mpg screen shot of the mpg on the last tank (95% highway):

So no real mpg loss.

@gifuboiler , any reason you are considering clubbing up? You shouldn’t be seeing any oil burn yet on that 2014. How many miles on it now? It looked good when we did the second key a couple of months back.

Keep us posted .

 

Another thread not too long ago a few folks like the 0W-40 for Prii...cannot recall if it was for Gen3...but why not. MOTUL was one brand discussed. Some feel the 40 weight keeps the engine quieter, especially as the oil gets a little into mid drain interval.